Process of treating crude ferrochromium and producing solid ingots.



UNITE STATES PATENT OFFICE.

JAMES TURNER MOREHEAD, OF. NEW YORK, N. Y., AND JOHN B. HUFIEARD, OF FERRIS,

WEST VIRGINIA, ASSIG-NORS TO ELECTRO METALLURGICAL COMPANY, OF OHI- OAGO, ILLINOIS, A CORPORATION OF WEST VIRGINIA.

PROCESS OF TREATING CRUDE FERROCHROMIUM AND PRODUCING SOLID INGOTS.

No Drawing.

have invented certain new and useful Improvements in Processes of Treating Crude Ferrochromium and Producing Solid Ingots, of which the following is a specification.

In the manufacture of chrome steel, it is customary to dissolve-in molten open-hearth or crucible steel pieces of a ferro-alloy containing upward of forty per cent. of chromium, produced for, example by the reduction of chromite in 'an electric i furnace. While the chromium addition greatly increases the hardness of the steel. and itsresistance to shock, without rendering it unforg'eable, it is difficult to predetermine the amount of ferrochromium which should be added to produce steel of required composition and characteristics, for the reason that the pieces of added ferrochromium usually contain occluded gases which, together with atmospheric air, oxidize an indeterminate percentage of the chromium when the alloy is raised to the temperature necessary to effect its solution in steel. Some commercial chrome steels will therefore be found to contain mere traces of chromium.

The present invention is a process of producing solid ingots or pieces of ferrochromium, as well as a product which isless subject to loss of chromium by atmospheric oxidation, when added to steel. According to this process the molten crude ferrochro mium is treated with silicon, or a silicid or silicon-alloy of some metal whose addition to chrome-steel is unobjectionable. Ferrosilicon is a suitable reagent and may be used by placing pieces of the silicid in the bottom of the vessel and tapping the molten ferrochromium from the electric. furnace onto it. The silicon removes the dissolved gases which would otherwise form blowholes in the cast ferrochromium and reduces any metallic-oxids which may, be present. In practice, it is desirable to add a. sllght excess Specification of Letters Patent.

Patented Mar. 25, 1913.

Application filed July 10, 1907. Serial No. 383,107.

of silicon. This residue of silicon in. the finished ferrochromium is useful when the alloy is added to steel, in that it prevents oxidation of chromium and the formation of blowholes, reduces metallic oxids and removes the dissolved gases.

The purified molten ferrochromium, with the excess silicon therein, if present, is cast into ingots, either by tapping it into molds of any desired size and shape or by allowing it to solidify in the treating vessel.

The term ferrochromium, as used in the present description and claims, refers to a product in which the chromium is the essential and valuable constituent, constituting 50% and upward of the commercial product.

Ve claim:

,1. The process of-treating molten chromium alloys, which comprises protecting the chromium from oxidation upon further alloying and reducing oxids of chromium therein by adding a reagent containing silicon to the molten alloy.

2. The process of treating molten chromium alloys, which comprises protecting the chromium from oxidation upon further alloying and reducing oxids of chromium tllilerein by adding ferrosilicon to the molten a oy.

3. The process which consists in treating crude molten ferrochromium with ferrosilicon containing sufiicient silicon to remove occluded gases and leave a residue of silicon.

4. The process of. producing solid ingots of ferrochromium, which consists in treating crude molten ferrochromium with ferrosilicon containing sufiicient silicon to remove occluded gases and leave a residue of silicon, and casting the product.

' In testimony whereof, we affix our signatures 1n presence of two witnesses.

JAMES TURNER MOREHEAD. J OHN B. HUFF'ARD. Witnesses for Morehead:

E. F. PRICE, F. E. DAVIDSON. Witnesses for Hufiard:

I. vR. EDMANDS, [j GEO. T. LANCASTER. 

